1. Field of the Invention
This invention relates in general to the construction of furnaces and in particular to a new and useful combustion furnace particularly a refuse incinerator which includes a double metal wall construction and a shield plate spaced inwardly from the walls surrounding the metal grate at least in the area in which the grate is close to the furnace walls and with means for directing air into the space between the metal walls for flow through openings therein to the space between the inner metal wall and the metal shield plate and for eventual flow through openings in the shield plate to the furnace chamber.
2. Description of the Prior Art
Walls of refuse incinerators are usually made of solid masonry even in the fire zone which is in the vicinity of the hearth or a grate upon which the material is burned. With such furnaces the temperature on the inner surface of the furnace walls can rise to such values that the ashes coming into contact with the wall are melted and deposited thereon in the form of coarse slag beads especially in the areas of the furnace walls which are directly adjacent the grate. These formations tend to increase in size inwardly so that they obstruct the grate and they must be cut off periodically. This is a time consuming process and requires cooling and subsequent reheating of the furnace and the stoppage of the furnace may take up to several days. In addition the cutting off of the slag which forms usually causes damage on the furnace walls and makes repair work necessary.